This invention is made with no United States government support.
The present invention relates generally to medical instruments and medical imaging, and more particularly to, a method and apparatus to provide percutaneous images to assist in performing an accurate tissue biopsy in which nuclear medicine tracer uptake is localized using a radionuclide detector, and then an ultrasound probe is used to obtain anatomical ultrasound images.
In breast cancer patients, the lymph node is a very common site of secondary tumor formation. Evaluation of the lymph node in the ipsilateral side of the patient is used as an early monitor of metastasis. Many patients being treated for breast cancer undergo xe2x80x9caxillary dissectionxe2x80x9d to examine the lymph nodes. Because of their small size and diffuse distribution however, axillary dissection is surgically difficult and often physically traumatic for the patient. That is, one of the most common side effects after a patient undergoes breast cancer surgery is xe2x80x9clymphedemaxe2x80x9d, which causes painful, and often permanent, swelling in the arm on the side of the surgery. Lymphedema results from the removal of the 10-12 lymph nodes nearest the breast. In the past, these lymph nodes were surgically removed to check for the spread of the tumor.
More recently, a technique has been employed call sentinel node biopsy. In this procedure, a small amount of radioactive dye is injected near the tumor. The blood stream leaving the tumor will carry any metastasizing cells to the first lymph node downstream. A radionuclide device, much like a Geiger counter, is then used to locate the node net the tumor, which is known as the sentinel lymph node, by monitoring trace uptake. The sentinel lymph node can then be removed and tested, If the sentinel lymph node is clear of cancerous tissue, no other nodes need to be removed. This procedure has resulted in the avoidance of the removal of all the lymph nodes in approximately two-thirds of women who have had breast cancer surgery. However, the outcome of this procedure and the effects to the patient, are largely dependent upon the palpation skills of the surgeon. The detection of the sentinel node by the Geiger counter-type device helps guide the surgeon, but is anatomically imprecise. Therefore, accurately locating the sentinel lymph nodes is critical in performing such a procedure to eliminate the chances of lymphedema and to make the procedure as non-invasive as possible. However, even with the use of the existing radionuclide probe, when a surgeon performs this procedure, it is still an open surgical procedure, and therefore more invasive than may be necessary.
It would therefore be desirable to have a method and apparatus capable of accurately tracking tracer uptake and determining the depth of maximum tracer uptake, and once the maximum tracer uptake depth is determined, imaging anatomical structure so that a tissue biopsy can be performed as non-invasively as possible.
The present invention relates to an instrument used in a method of providing percutaneous images to assist in performing an accurate tissue biopsy and a system to locate nuclear medicine tracer uptake within a living being, that overcomes the aforementioned problems.
The present invention includes a medical instrument that combines an ultrasound probe with a focusing radionuclide detector that is capable of detecting the depth of tracer uptake to perform ultrasound-guided percutaneous tissue biopsy. The area of maximum tracer uptake is localized by the medical instrument and the depth of the maximum tracer uptake is determined. The resulting image displays the radioactivity detected by the radionuclide detector as a colored representation on a typical grayscale ultrasound image. The color overlay can be either completely shut off, or faded, so that the radiologist or surgeon can perform the ultrasound-guided core biopsy using existing ultrasound biopsy software. Such software superimposes a white line, representing the expected needle track, on the ultrasound image to plan the approach to avoid vital structure and minimize the invasiveness of the procedure.
Therefore, in accordance with one aspect of the invention, a medical instrument is disclosed having an ultrasound probe capable of percutaneous detection of anatomical structure within a living being, and a radionuclide detector capable of detecting depth of tracer uptake within the living being. The radionuclide detector is coupled to, and in operable association with, the ultrasound probe such that at least one of the radionuclide detector and the ultrasound probe is pivotally moveable with respect to the other. In order to determine depth of tracer uptake, a fan array of radionuclide detectors can be used in which each of the radionuclide detectors in the fan array are pivotal with respect to one another so that a line of sight extending from each of the radionuclide detectors intersect at a moveable focal point. Alternately, a pair of radionuclide detectors can be arranged on either side of the ultrasound probe with a line of sight from each radionuclide detector converging at a moveable focal point. The moveable focal point is used to determine the precise point of maximum radioactivity.
In accordance with one aspect of the invention, a method of providing percutaneous images to assist in performing an accurate tissue biopsy includes localizing radioactivity within a portion of a living being by passing a radionuclide detector across a surface of the living being and then imaging anatomical structure within the portion of the living being with a probe on the surface of the living being about the localized radioactivity. The method also includes superimposing an image representation of the localized radioactivity with an image of the anatomical structure about the localized radioactivity.
In accordance with yet another aspect of the invention, a system is disclosed to locate nuclear medicine tracer uptake within a living being. The system includes a medical instrument having an ultrasound probe producing anatomical structure detection signals and a radionuclide detector producing nuclear detection signals. The radionuclide detector is pivotally connected to the ultrasound probe such that a line of sight from the ultrasound probe and a line of sight from the radionuclide detector converge at a focal point. The focal point is adjustable to determine a depth of tracer uptake in an anatomical structure. An interface unit is provided to integrate the anatomical structure detection signals with the nuclear medicine detection signals to provide a grayscale ultrasound image superimposed with a color image indicative of tracer uptake. A display is provided to receive the integrated anatomical structure detection signals and nuclear medicine detection signals to display the superimposed grayscale ultrasound image and color image.
By combining an ultrasound imaging and radionuclide detection imaging, in real time, a core tissue biopsy can be done under ultrasound visualization by a radiologist, rather than a surgeon, which would lower cost of the procedure while at the same time lessening the physical impact on the patient compared to axillary dissection because the exact depth of the tracer uptake can be determined. One particular application of the present invention includes locating the sentinel lymph node in a breast cancer patient in which the sentinel lymph node can be located precisely by radionuclide imaging and then ultrasound imaging can be added to perform the tissue biopsy. Such a percutaneous biopsy would be less invasive than the aforementioned radionuclide probe procedure, and although complications associated with the radionuclide probe procedure are relatively low, with this percutaneous approach, it is expected that the rate of complications would be further reduced.
Furthermore, by converting sentinel lymph node biopsy from a surgical to a radiological procedure, it is believed that the cost of the procedure can be reduced, which may permit increased access to this procedure for more women. Finally, even if the surgeon and patient decide that complete removal of the sentinel lymph node is desired instead of ultrasound-guided core biopsy, the localization method described herein can be used to guide a marking needle and hookwire into the sentinel lymph node. This is similar to the method used to localize breast lesion. The surgeon can then follow the wire directly to the lymph node, with a significant decrease in surgical dissection, resulting in decreased morbidity.
Various other features, objects and advantages of the present invention will be made apparent from the following detailed description and the drawings.